diff --git a/libnfc/buses/Makefile.am b/libnfc/buses/Makefile.am
index a875ed7..dcaeddd 100644
--- a/libnfc/buses/Makefile.am
+++ b/libnfc/buses/Makefile.am
@@ -13,7 +13,7 @@ libnfcbuses_la_SOURCES += spi.c spi.h
 libnfcbuses_la_CFLAGS +=
 libnfcbuses_la_LIBADD +=
 endif
-EXTRA_DIST = spi.c spi.h
+EXTRA_DIST += spi.c spi.h
 
 if UART_ENABLED
   libnfcbuses_la_SOURCES += uart.c uart.h